I actually just got Apache to start a few minutes ago - don't ask me how!
I'm running them on Xen virtual servers, and I'm still getting the bugs out. I've never used virtual before now. When I do /etc/init.d/apache2 restart, it gves me that same error twice:

In a related question. Should I have installed ISPConfig 3 using the expert install in the second server? I'm running two physical machines, both having two virtual ones running HAProxy/heartbeat in one, and ISPConfig3/Apache in the other. I'll be using a bridge and crossover to do replication and rsync.